Water-cooled sliding combustion grate having a parallel drive

ABSTRACT

The invention relates to a water-cooled sliding combustion grate, comprising a combination of movable grate plates ( 6 ) and stationary grate plates ( 5 ). The length of the grate plates ( 5, 6 ) passing over the grate track width is more than 6 meters. The movable grate plates ( 6 ) are driven by one parallel drive each, which comprises two separate drive units, which can each move a respective end area of a movable grate plate ( 6 ) back and forth, wherein the two drive units can be synchronized. To separate the primary air transversely over the grate track over a plurality of areas, at least one partition can extend along the grate track under the grate. Each partition is moved along with the lower faces of the grate plates ( 5, 6 ) at the upper edge of said partitions so that said partitions are fully connected everywhere to the lower faces of the grate plates.

The invention pertains to a water-cooled siding combustion grate forrefuse incineration plants which are especially suitable for burning ofinhomogeneous refuse and waste with partially high heating values. Suchsliding combustion grates have fixed and movable grate stages made ofgrate plates or made of a row of grate bars in which the grate platesare laid out on top of each other in a stairway formation. These gratescan be installed in such a way that the combustion bed basically lieshorizontally or else inclined, whereby slopes of 20 angular degrees ormore are common. Grate plates are preferably made of steel sheets andthey form board-shaped hollow bodies which extend over the completewidth of the grate track. Water is channelled through these as a coolingmedium. Every second grate plate is designed so as to be movable in thelongitudinal direction and can therefore execute a sliding or feedingstroke. When it concerns the feed grate, the movable grate plates canpush the incinerator charge with their front side to the next underlyinggrate plate. On the other hand, a reverse feed grate forms a virtuallyinverted, integrated, inclined staircase with overlapping steps. In thecase of a reverse feed grate, the front sides of the movable grateplates carry the incinerator charge lying behind them back, after whichthis is again milled downwards in the direction of the slope of thegrate. The movable grate plates, i.e. the respective grate plateslocated between two fixed grate plates, are moved to and from in thedrop direction of their slope. This ensures that the refuse burning onthe grate is constantly relocated with a high retention time of 45 to120 minutes and is equally distributed on the grate.

European patent document, EP-0 621 449, refers to a water-cooled slidingcombustion grate. This grate has grate plates which stretch over thecomplete width of the grate track and do not consist of multiple gratebars per grate stage. Like the stationary grate plates, the movablegrate plates are fixed at the back to crossbars which collectively moveforwards and backwards during operation and hence move the movable grateplates. European patent document, EP 0 874 195, shows a special designof such a grate with individual drives for every single movable gratestage. Here the movable grate plates roll on the steel rolls and arealso laterally guided on the horizontal rolls along the lateral endplanks. The drive is implemented with each hydraulic piston-cylinderunit per grate plate, which impinges on the grate plates from the rear,approximately at the centre and is located under the grate.

The previous water-cooled sliding combustion grates were assembled withwidths of approx. 3 m to 6 m, which means that a sliding combustiongrate is composed of grate plates which extend over this width and arealso 3 to 6 meters long. Such a sliding combustion grate with laterallyrestricted planks is designated as a grate track. The drive occurs foreach movable grate plate with the help of a centrally arranged,individual hydraulic cylinder-piston unit below the grate and behindmovable grate plate, as described and illustrated in European PatentDocument EP 0 874 195. The grate plates are laterally guided at thelateral planks by means of horizontal steel rolls. The planks laterallyrestrict such a combustion grate.

The following disadvantages could be observed with such an individualdrive compared to a previously practised mode of operation where themovable grate plates were operated collectively by a central,proportionally large dimensioned cylinder-piston unit and were laterallyguided at the side planks without rolling support and insteadabrasively: Previously, tiny particles could get stuck laterally betweenthe grate plate and the lateral end cover plate of the side planksduring operation leading to a lateral tilting of the grate plate, whichmeans that the grate plate was no more exactly parallel to theneighbouring stationary grate plates when seen from above. If it ismoved in this condition, the plate impinges on the lateral end plateswith a huge leverage that develops as a result. The necessary drivingforce becomes correspondingly greater. The wear caused by the hugefriction force was considerable and minimised the lifetime of thecomplete grate. The individual drive of the single movable grate platesshown in the European paten document EP 0 874 195, enables anoptimisation of the combustion process by means of a systematic localfeed and a systematic local transportation of the incinerator charge.The laterally rolling bearing leads to a minimisation of the wear and areduction of the necessary driving force.

Wider grate tracks are always desirable with increasing capacityrequirements. However the drive with a central cylinder-piston unitreaches its threshold in case of longer grate plates or larger gratetrack widths, in spite of lateral rolling guidance or lateral bearing ofthe grate plates with the help of steel rolls at the lateral grateplanks. In particular, the grate plates post a threat of tilting with awidth of more than 6 meters. The traditional drive solution for themovable grate plates is moreover present underneath the grate in themiddle of the grate plates and is accessible there only when the grateis not in operation. And even if it possible to realise a grate with agrate track width of, for example, 10 meters, it would result in theproblem that the primary air that is supplied downwards may not besystematically used depending on the waste composition because such awide combustion grate and a wide grate track cannot be permanently fedwith a necessarily homogeneous distribution of similar combustibleincinerator charge. It also happens that a specific amount ofincinerator charge accumulates over the width of the grate or the gratetrack due to inhomogeneous refuse and this material burns significantlyeasier than any other accumulation on the same grate plate or on thesame longitudinal section of the grate track. It would result in theprimary air streaming highly unevenly and incorrectly from bottom to topthrough the combustion grate. Where the incinerator charge is easilycombustible, there would be a significant excess of primary air becauselittle flow resistance would be registered there and where theincinerator charge is poorly combustible, there would be a higher flowresistance and correspondingly less flow of primary air. The easilycombustible incinerator charge would therefore burn rapidly and thepoorly combustible incinerator charge lying nearby would burn poorly ornot at all due to inadequate supply of primary air because theincinerator charge itself obstructs the primary air vents.

Conventional grates are already equipped with partitions for primary airsupply in the longitudinal direction. There it concerns stationarypartitions installed underneath the grate and particularly underneaththe stationary grate plates. Thereby the combustion grate can be exposedto different primary air pressures in, for example, three or fourdifferent sectors along the length of the grate track. A partition ofprimary air supply across the width of the grate track has not beentried previously, or it is realised across multiple grate tracks locatednext to one another, in that easily or poorly separated combustiblewaste in them is burnt. A primary air separation however becomesimportant in the case of an even larger grate width without separationof the tracks because the difference in qualities of waste distributedover the grate width is often unavoidable.

The objective of the present invention is therefore to create awater-cooled sliding combustion grate which, based on state of the arttechnology, is further developed in such a way that it enables therealisation of significantly wider grate tracks, i.e. grate tracks withwidths of 6 meters or more. In the process, a possible tilt of themovable grate plates should be effectively avoided in the case of grateplate lengths of more than 6 meters. Further, the drive should be easierto maintain, in that it is accessible in a special design during thecombustion operation and the hydraulic piston-cylinder units of theindividual drives of the grate plates can be replaced without the needfor interrupting the operation of the grate. The primary air feed ofsuch a combustion grate with extra wide grate track should also beseparable over its width in a particular arrangement.

The objective is achieved by a water-cooled sliding combustion gratecomposed of movable grate plates or of movable grate plates which arealternately combined with stationary grate plates, in which these grateplates lie on top of each other in a step-like manner characterised by ameasurement of more than 6 meters for the length of the grate platespassing through the width of the grate track, wherein they are supportedupon intermediate steel girders. The movable grate plates are driven bya parallel drive made of two separate drive units. Each end of a movablegrate plate can be moved forwards and backwards by means of such a driveunit, in which the two drive units can be synchronised.

First a sliding combustion grate with a conventional hydraulic drive isillustrated in the drawings and then this special water-cooled slidingcombustion grate with parallel drive and primary air separation ispresented here and its functions are further described below with thehelp of drawings.

It shows:

FIG. 1: A sliding combustion grate with conventional drive inperspective view with partially removed grate plates;

FIG. 2: A longitudinal section through the grate track, with a viewperpendicular to the grate track and the conventional hydraulic drivesintegrated under it;

FIG. 3: The basic principle of an individual drive unit of the two driveunits of the parallel drive of a movable grate plate that are locatedlaterally to the grate;

FIG. 4: A perspective representation of a longitudinal section of thesliding combustion grate with parallel drive of the individual movablegrate plates according to the invention;

FIG. 5: A cross-section transverse to an edge of a grate track with asingle hydraulic drive unit outside the side wall for the grate platelocated to the right of the viewing direction;

FIG. 6: A diagonal view from below the sliding combustion grate with apartition for the primary air supply across the width of the gratetrack.

FIG. 7: A lateral view of a single-track grate with parallel drive;

FIG. 8: A lateral view of a single-track grate with parallel drive andwith the elements installed behind the side wall;

FIG. 9: A total view of the single-track grate with parallel drive witha view of the upper side of the grate;

FIG. 10: A total view of the single-track grate with parallel drive witha view of the underside of the grate;

The basic construction of a conventional sliding combustion grate withits important elements, how it is presented during the construction,where the individual grate plates are still missing and the view of thesubstructure are evident from FIG. 1. Here it concerns a grate with agrate track width of approx. 2 m inclined downwards in the direction offlow. Two vertical, lateral steel walls 1,2, parallel to one another,are connected stably to one another with distancing bars 3,4. Thesedistancing bars 3,4 run perpendicular to the grate and extend across theinside width between the two vertical steel walls 1,2 at two differentlevels. Both the steel walls 1,2 to the left and right of the grate canthereby consist of multiple steel sheets or parts which are screwed toone another in a suitable manner. Distancing bars 3,4, threaded at bothends, penetrate the two vertical steel walls 1, 2 and are screwedtightly to the vertical steel walls 1,2 by means of tapered ends andnuts. The top level of distancing bars or crossbars 3 also serve assupport rods for the stationary grate plates 5 lying on top of them. Thefront edge of the bottom stationary grate plate 5 abuts against adischarge lip 7 welded in place between vertical steel walls 1,2, whileits rear section is suspended over the first top distancing bar orcrossbar 3. Next in line is a movable grate plate 6, the front bottomedge of which rests on the first stationary grate plate 5 below. Thefront bottom edge of the next highest stationary grate plate 5 rests inturn on movable grate plate 6 and so on. The sloped front side of theindividual grate plates 5,6 is perforated by primary air slots 8,through which the primary air for the combustion is blown from belowinto the incinerator charge. Along the upper edge of steel walls 1,2 aretwo square tubes 9,10 disposed on top of each other in a slightly offsetmanner, the lower ends of which are sealed by welding, in that they arewelded there. These square tubes 9,10 constitute the side panels of thegrate track and restrict the sides of the incinerator charge bed whenthe grate is in operation. They are water-cooled and are forciblyflooded with water from bottom to top so that their insides are alwayscompletely filled with water. The individual grate plates 5,6 are madefrom sheet steel and are designed as hollow bodies that are forciblyflooded with water so that their insides are always completely filledwith water and no air bubbles can be present inside. Alternatively, thegrate plates consist of a support framework in which a free-flowinghollow body is inserted as a cooling body whereby this can then becovered by a wear plate which is interlocked with the support frameworkand the cooling body to ensure good heat transfer. All the sheet steelparts of the grate, whether square tubes 9,10 or grate plates 5,6, thatcome into contact with the incinerator charge are, therefore,continuously covered with water on the back side of the steel sheet orat least cooled by a water-cooled heat sink. Hence all the parts incontact with the fire are cooled continuously and kept at a stabletemperature so that practically no dilatation occurs. This eliminatesthe need to provide compensating elements of any kind to the sides ofthe grate plates. The stability of the grate construction is essentiallyachieved by the distancing bars or crossbars 3,4, which strut and bracethe two outer steel walls 1,2 on two parallel levels as alreadydescribed. Between these two levels of crossbars 3,4, running along thegrate on both sides of its centre are two other hollow profiles in theform of square tubes 11,12, which are connected at the bottom and at thetop at some points to the crossbars 3,4, running perpendicular to them.One of the square tubes, namely square tube 11, feeds the cooling waterfrom bottom to top for grate plates 5,6, while the other square tube 12supplies flushing and cooling air for the hydraulic components of thedrive of the movable grate plates 6. Support members 13 are installedfor movable grate plates 6 between these two parallel-running squaretubes 11,12. These support members 13 are fixed to the square tubes bytwo bolts that run through the two square tubes 11,12. For this purpose,the square tubes or hollow profiles 11,12 have welded-in crossbars withan inside diameter designed to accommodate the retaining bolts for thesupport members 13. The support members 13 themselves each have steelroll 16 disposed parallel to the corresponding grate plate plane, aswell as a steel roll 17,18 to the left and right acting in the verticalplane. The movable grate plate 6 rolls off the last and the horizontalsteel roll 16 serves as a lateral guide at the rear side of the grateplate 6. Till a hydraulic cylinder-piston unit 21 with pistons 22 isinstalled between the Support member 13 and the movable plate lyingbefore it. At the planks, i.e. at the square tubes 9,10, two horizontalsteel rolls 19,20 are constructed for every movable grate plate 6 andthese rolls are laterally guided into the plates from outside.

FIG. 2 shows an area of this conventional grate according to FIG. 1 withthis conventional drive of the movable grate plate 6 as a longitudinalsection seen from the side. The hydraulic cylinder 21, whose piston rods22 reach the interior framework of the movable grate stage 6, can berecognised and the hydraulic cylinder 21 is hinged to a Support member13 with its rear side. At the rear, the grate plate 6 rolls off on therolls 17 of the support member 13 which is fixed to the square tubes11,12 by means of both bolts 14,15. Each of these support members 13 canbe tilted backwards by removing the rear bolt 14 after which the pivotpoint of the hydraulic cylinder 21 is accessible and this can be readilydismantled. That can however take place only after decommissioning ofthe grate. The square tube 10 can be recognised behind the grate plates5,6 which forms the lateral plank and below the side wall 2 with thecrossbars 4.

The hydraulic drive is located directly under the grate plates andalways at their centre in the case of these present constructions asshown in FIGS. 1 and 2. A parallel drive of the movable grate plates isnewly realised in the sliding combustion grate introduced here whichenables the realisation of significantly wider grate tracks andeliminates the need for lateral guiding of the grate plates with theirown steel rolls. For this purpose, every movable grate plate is drivenindividually on its two side ends or on its lateral ends, whereby thetwo individual drives for every movable grate plate can be perfectlysynchronised with one another. A single drive unit on one side of amovable grate plate 6 is shown as a schematic diagram in FIG. 3. Aconnection rod 30 acts on the movable grate plate 6. This connection rod30 is connected to a crank 31 which sits on a crankshaft 32. The crank31 has a slotted hole 38 in which the bolts 39 of the connection rod 30are mounted because the connection rod 30 must move back and forthlinearly in the direction of its course as shown with a double arrowwhen the crank 31 pivots back and forth angularly and consequently itsend does not carry out a linear motion. The crankshaft 32 is supportedin a bushing 33 which penetrates the side wall of the grate constructionand is stably welded or screwed to this, namely at the point indicatedwith an arrow. On the outside of the grate construction, the crankshaft32 is equipped with another crank 34 which is hinged to the end of apiston rod 35 of a hydraulic cylinder 36. The cranks 31,34 can be simplyplugged in at the crankshaft ends and can be secured with a lock nut.With its other end, the hydraulic cylinder 36 is hinged to a retainingbracket which is fixed to the outside of the side wall of the grateconstruction. The axle of the bushing 33 runs at a right angle to thedirection of motion of the movable grate plate 6 and the crank 31 forthe connection rod 30 at the crankshaft 32 can be mounted to the crank34 at the other end of the crankshaft 32 by swivelling by approx. 120°to 180°. When the crank 34 is actuated at this other end of thecrankshaft 32 and the crankshaft 32 is turned correspondingly, thevisible end of the movable grate plate 6 is accordingly moved forwardand backwards as with the forward and backward movements of the piston35 by means of the hydraulic cylinder-piston unit 35, 36. The crankshaft32 can be turned by 0° to approx 60° by means of systematic controllingof the hydraulic piston-cylinder unit 35,36 so that the degree of thrustof the movable plate 6 can be continuously varied. An identical drivefor the movable grate plate 6 is located at the other side of the gratetrack so that a parallel drive is formed. Proportional valves incombination with a position measuring system for the hydraulicpiston-cylinder units enables accurate synchronisation of extension andretraction so that the movable grate plates 6 driven by them always moveexactly parallel to the stationary grate plates 5. The hydrauliccomponents are installed completely outside the grate construction withthis drive design. Thereby, only the heavy mechanical parts of theoverall drive design, which themselves cannot have any other parts, areexposed to the abrasive effect of the downdraught. The drive parts thatare sensitive to the downdraught are outside the grate and are alwaysaccessible there even during the operation of the grate.

The hydraulic components are situated further away from the grate withthis drive construction and are no more directly beneath the grate.Every single movable grate stage can be operated in this way via its twoown hydraulic cylinder-piston units which are fixed to the two sidewalls on the outside of the grate construction and can be operatedindividually compared with all other movable grate plates, All othermovable grate plates are operated in a similar way by pairs of hydraulicdrives.

A perspective representation of the sliding combustion grate withparallel drive of the individual movable grate plates 6 according to theinvention is shown in FIG. 4. The hydraulic cylinder-piston units 36with a piston and the associated crank 34 and crankshaft 32 with abushing 33 to its bearing can be perceived at the side wall 2 visiblehere and the local crank 31 and connection rod 30 for operation of amovable grate plate 6 on one side of it is visible on the other side.Both the ends of the movable grate plates 6 are provided with suchhydraulic drives so that every movable grate plate 6 has an individualparallel drive. This drive type enables realisation of wider gratetracks than those known previously. Two to four and more conventionalgrate tracks can be replaced with one individual, single track grate. Nodilatation problem develops because the water-cooled grate plates can bemaintained within a narrow temperature band due to its cooling. Thebending stress of the grate plates in the direction of motion isexceptionally high due to the flat design of the grate plates 6 and doesnot present any impediments for the operation of grate plates more than6 meters in length. The grate plates can be made of multiple segments,which are tightly screwed to one another, across the width of the gratetrack. The steel framework is preferably installed as segments whichhold a hollow body that can be placed in and guided through them and arethen screwed on to a wear plate in thermal contact with the hollow body.Owing to this parallel drive, grate tracks with continuous grate platesof 10 m, 12 m or longer and thus corresponding grate tracks of the samewidth can be constructed. Only the load on the grate plates 6 as aconsequence of the incinerator charge lying on it must be absorbedthrough further support structures. The grate plates 5,6 are designed ina board shape, longer than wider or taller and cannot act as a selfsupporting bridge over a length of 12 meters and more or a track widthof 12 meters or more in spite of its internal structure. To absorb thisload, the substructure of the grate has one or more steel girders 45which are installed in the longitudinal direction of the grate track andact as rails. The grate stages are also adequately stiff in the drivedirection, which means no additional auxiliary constructions such asgrate carriages, transverse shafts or similar are required. Only theweight of the grate and that of the refuse lying on top of it is carriedby the longitudinal beams 45. Such a grate track width can hardly berealised with the conventional grate bars made of cast iron due to thesmall width of the grate bars. Also an auxiliary construction would berequired with such elements. Three steel girders 45 are installed in theexample shown so that the grate plates 5,6 can be supported for all the3 meters in the case of a grate track width of 12 meters. The stationarygrate plates 5 rest directly on these steel girders 45 while the movablegrate plates 6 are provided with steel rolls on their underside andthese steel rolls then roll on the upper side of these steel girders 45,whereby the load due to the incinerator charge and the own weight of thewater-cooled grate plates 5,6 are borne by these steel girders 45.

The layout of the hydraulic cylinder-piston units outside the gratetracks are as illustrated and described above, that means outside at theside walls 1,2 of the grate construction, has an advantage that thesecomponents are accessible at all times and are also exposed to littlerisk of fire than when located underneath the grate. However theparallel drive introduced here can also be implemented in such a waythat the hydraulic drives are designed in the same way instead of in themiddle of every grate plate as previously arranged. However they arereplaced by two such drives which are located at both the ends of thegrate plates. The parallel drive is also implemented in this way andboth the hydraulic cylinder-piston units can be extended and retractedwith accurate synchronisation by means of proportional valves incombination with a position measuring system, so that the movable grateplate 6 driven by the units always moves exactly parallel to thestationary grate plates 5.

A cross-section through the grate track with a view of the rear in thedirection of motion of the movable grate plate 6 is shown in FIG. 5. Aconnection rod 30 is hinged to a recess at the bottom of the grate plate6. The connection rod 30 is flexibly connected to the crank 31 which isat the bottom of the crankshaft 32 via the bolts 39. The crankshaft 32is supported in the bushing 33 by means of the replaceable slide bearing40. The bushing is stably connected to the side wall 1 of the grateconstruction via the vane struts 41. These vane struts 41 are integratedwith the corresponding recesses in the side wall 1 or 2 of the grateconstruction and are welded to them. The drive is present on the otherside, of which the crank 34 and the piston rod 35 are illustrated in asection here. In this example, these two elements are arranged above thecrankshaft 32 contrary to the variants in FIGS. 3 and 4. The assembly ofthe hydraulic cylinder-piston units can however be freely chosendepending on the space conditions.

FIG. 6 shows a section of a grate track seen diagonally from below witha partition over the length of the grate track for the primary airsupply. The problem due to the increasing width of a grate track is thatthe incinerator charge on the grate is not homogeneous when seen overthe width of the grate. When a single, uniform primary air pressure isused over the complete width of the grate, the easily combustibleincinerator charge receives more air because it obstructs the primaryair supply vents for a shorter period while the poorly combustibleincinerator charge heavily covers the primary air supply vents in thegrate plates and suppresses an efficient air supply. The opposite ofwhat is required occurs, namely that the easily combustible incineratorcharge is especially supplied adequately with primary air while thepoorly combustible incinerator charge is correspondingly supplied withlesser primary air. Also the poorly combustible incinerator chargehardly burns while the easily combustible incinerator charge has alreadyburnt down. A uniform burn-up can be achieved when the primary airsupply does not take place with uniform pressure over the complete widthof such a wide grate track. A separation of the primary air zones acrossthe width of the grate is however a prerequisite for this. It isrealised as shown in FIG. 6. A vertical partition 46 extends here alongthe grate track under the grate, its stationary grate plates 5 and itsmovable grate plates 6. The partition 46 is guided with its upper edgeto the underside of the grate plates 5,6 so that it completely attachesitself to the underside and a lasting seal between the two sides of thepartition 46 is created. The partition 46 has a recess 47 behind themovable grate plates 6. A separator plate 48 is added to the rear sideof the movable grate plates 6 which covers this recess from one side andoverlaps the partition 46. Thereby, the recess in the partition 46 isalso dosed and when the movable grate plates 6 are moved, the separatorplate 48 at the partition 46 is moved forwards and backwards sealedtightly across the recess 47. The partitions 46 are sealed underneath tothe floor of the grate construction and the chambers thus formed arealso sealed at the front and back. They form a separate primary aircompartment which extends beneath the grate track across its overalllength. But this compartment can be additionally sub-divided intodifferent longitudinal compartments across the length of the gratetrack, in which the corresponding partitions 49 are installed. Thereby,an entire matrix of primary air compartments is created, in which everyindividual compartment can be equipped with a separate primary airsupply. Correspondingly the combustion can be controlled individuallyaccording to air requirement at each position above a primary aircompartment with its own primary air pressure.

The piston-cylinder units of the parallel drives can also be arranged inother mounting directions as shown in FIG. 4, depending on the spaceconditions. The individual hydraulic cylinders are preferably arrangedin a staircase manner over one another and mounted on the outside of theside wall. In the case of vertically arranged cylinders, the cranks atthe crankshaft must be rotated by 90°. In the case of cylinders tiltedat an angle of 45°, they should correspondingly be rotated by 45°opposite to the execution shown in the figures. To gain some space,multiple alignments can also be chosen interchangeably.

The lateral view of a single-track grate with parallel drive is shown inFIG. 7 in which the drive elements are installed differently thanpreviously illustrated. The hydraulic cylinder-piston units 36 areinstalled at an oblique angle outside the side wall 1 and the pistonsact on the cranks 34 diagonally from below. The cranks then turn thecrankshaft in the bushing 33. As seen in FIG. 8, the crankshaft thenswivels the crank 31 located under the grate and over the connection rod30 of the movable grate plate 6. These elements are located behind theside wall 1 of the grate construction and are nevertheless marked inFIG. 8, namely the stationary grate plates 5 and the movable grateplates 6.

The single-track grate with parallel drive is shown completely in FIG. 9with a view of the grate surface, diagonally from above. One canrecognise the drive elements from the hydraulic cylinder-piston unit 36,the crank 34 and the bushing 33 installed laterally on the side wall 1.These drive elements support the crankshaft. Finally, the same grate asseen diagonally from below is illustrated in FIG. 10, seen from theother side of the grate. Therefore the underside of the grate can beseen. Movable grate plates 6 alternate with stationary grate plates 5and the drive elements on the internal side wall 1 visible here areinstalled on the same, namely the bushing 33 which penetrates the sidewall, the cranks 31 and the connection rods 30 actuated by them formoving the movable grate plates 6, so that they can carry out slidingand feeding strokes. Every single movable grate plate 6 can be movedindividually. It is clear that such a parallel drive at all the grateplates of a grate can be realised so that it is only composed of movablegrate plates.

The invention claimed is:
 1. A water-cooled sliding combustion gratecomprising: multiple movable grate plates (6) and stationary grateplates (5), wherein the grate plates (5,6) lie on top of each other in astep-like manner, and the grate plates (5,6) extend continuously acrossthe width of a grate track and have a length of more than 6 meters; twoindividual drive units for every movable grate plate (6) connected tolateral ends of the movable grate plate (6) forming a parallel drive foreach movable grate plate (6), each movable grate plate (6) being drivenindividually on lateral ends thereof by the two drive units, wherein thetwo drive units are synchronized with each other; and one or more steelgirders (45) disposed underneath the grate plates (5,6) in thelongitudinal direction of the grate track wherein the grate plates (5,6)are supported upon the one or more steel girders (45), and the load ofincinerator charge and the weight of the grate plates (5,6) are borne bythe one or more steel girders (45), and the movable grate plates (6)equipped with steel rolls on the underside thereof roll on an upper sideof the one or more steel girders (45).
 2. The water-cooled slidingcombustion grate according to claim 1, wherein the two drive units ofthe parallel drive of each movable grate plate (6) can be synchronisedby means of proportional valves in combination with a position measuringsystem for the hydraulic piston-cylinder units that are installed. 3.The water-cooled sliding combustion grate according to claim 1, whereineach of the two drive units of the parallel drive of each movable grateplate (6) comprises a hydraulic cylinder-piston unit (35,36) that isinstalled at outer side walls (1,2) of the grate outside the gratetrack, and the hydraulic cylinder-piston unit acts on a crankshaft (32)via a piston (35) and a crank (34), the crankshaft penetrates the sidewall (1,2) and another crank (31) with connection rod (30) is locatedunder the grate at other end of the crankshaft, whereby the connectionrod (30) has an impact on the movable grate plate (6).
 4. Thewater-cooled sliding combustion grate according to claim 1, wherein eachof the two drive units for the parallel drive of every movable grateplate (6) comprises a hydraulic cylinder-piston unit installedunderneath the grate adjacent to the internal side wall (1,2), whereinpistons of the drive units have an effect on outer ends of the movablegrate plate (6).
 5. The water-cooled sliding combustion grate accordingto claim 1, wherein at least one partition (46) extends along the gratetrack under the grate, the stationary grate plates (5) and the movablegrate plates (6) for separation of primary air across multiple sectionstransversely across the grate track, the partition (46) is guided withan upper edge thereof to the underside of the grate plates (5,6) so thatthe partition (46) is completely attached to the underside of the grateplates (5,6), the partition (46) has a recess (47) behind the movablegrate plate (6) so that the movable grate plate (6) can be moved in therecess (47), whereby a separator plate (48) is installed on the backsideof the movable grate plate (6) which covers the recess (47) from oneside and overlaps the partition (46).
 6. The water-cooled slidingcombustion grate according to claim 5, wherein multiple primary aircompartments are further realised in the longitudinal direction of thegrate track, in that further partitions (49) are installed vertical tothe partitions (46) in the longitudinal direction of the grate track sothat a matrix of primary air compartments is realised.
 7. Thewater-cooled sliding combustion grate according to claim 5, whereinevery individual primary air compartment can be provided with a separateprimary air supply at varying pressures.
 8. The water-cooled slidingcombustion grate according to claim 6, wherein every individual primaryair compartment can be provided with a separate primary air supply atvarying pressures.
 9. A water-cooled sliding combustion grate composedexclusively of movable grate plates (6) or of movable grate plates (6)which are combined with stationary grate plates (5), in which thesegrate plates (5,6) lie on top of each other in a step-like mannercharacterised by a measurement of more than 6 meters for the length ofthe grate plates (5,6) extending continuously across the width of agrate track, wherein the grate plates (5,6) are supported upon one ormore steel girders (45), the movable grate plates (6) are driven by aparallel drive made of two separate drive units, each end of a movablegrate plate (6) can be moved forwards and backwards by means of such adrive unit, in which the two drive units can be synchronized; wherein atleast one partition (46) extends along the grate track under the grate,the stationary grate plates (5) and the movable grate plates (6) forseparation of primary air across multiple sections transversely acrossthe grate track, the partition (46) is guided with an upper edge thereofto the underside of the grate plates (5,6) so that the partition (46) iscompletely attached to the underside of the grate plates (5,6), thepartition (46) has a recess (47) behind the movable grate plate (6) sothat the movable grate plate (6) can be moved in the recess (47),whereby a separator plate (48) is installed on the backside of themovable grate plate (6), and the separator plate (48) covers the recess(47) from one side and overlaps the partition (46).
 10. The water-cooledsliding combustion grate according to claim 9, characterised in thatboth the drive units of each movable grate plate (6) can be synchronisedby means of proportional valves in combination with a position measuringsystem for the hydraulic piston-cylinder units that are installed. 11.The water-cooled sliding combustion grate according to claim 9,characterised in that each of the drive units of the parallel drive ofeach movable grate plate (6) comprises a hydraulic cylinder-piston unit(35,36) which is installed at the outer side walls (1,2) of the grateoutside the grate track and which acts on a crankshaft (32) via a piston(35) and a crank (34), the crankshaft penetrates the side wall (1,2) andanother crank (31) with connection rod (30) is located under the grateat other end of the crankshaft, whereby this connection rod (30) has animpact on the movable grate plate (6).
 12. The water-cooled slidingcombustion grate according to claim 9, characterised in that each of thedrive units for the parallel drive of every movable grate plate (6) iscomposed of a hydraulic cylinder-piston unit which is installedunderneath the grate adjacent to the internal side wall (1,2), in whichpistons of the drive units have an effect on the outer ends of themovable grate plate (6).
 13. The water-cooled sliding combustion grateaccording to claim 9, characterised in that the one or more steelgirders (45) are installed in the longitudinal direction of the gratetrack for absorption of the load on the combustion grate, and act asrails on which the stationary grate plates (5) are supported and onwhich the movable grate plates (6) are mounted with rolling support, inthat the movable grate plates (6) are equipped with steel rolls on theirunderside.
 14. The water-cooled sliding combustion grate according toclaim 9, characterised in that multiple primary air compartments arefurther realised in the longitudinal direction of the grate track, inthat further partitions (49) are installed vertical to the partitions(46) in the longitudinal direction of the grate track so that a matrixof primary air compartments is realised.
 15. The water-cooled slidingcombustion grate according to claim 14, characterised in that everyindividual primary air compartment can be provided with a separateprimary air supply at varying pressures.
 16. The water-cooled slidingcombustion grate according to claim 9, characterised in that everyindividual primary air compartment can be provided with a separateprimary air supply at varying pressures.